1. Field of the Invention
The present invention relates to an apparatus and a method for detecting occurence of an abnormality in the warp positions with respect to a reed in a weaving machine or loom.
2. Description of the Related Art
Conventionally, woven cloth or finished fabric is subjected to an inspection process for checking the presence or absence of defects in the woven cloth. In this conjunction, it is however noted that such defect checking in the inspection process provides no effective means for remedying such a defect, which is brought about by an error or failure in inserting or drawing a warp through an inter-dent gap of a reed after breakage of a warp. As such a defect continuously makes appearance on the fabric in the warpwise direction, it should be detected as soon as possible, before it results in a serious problem of producing a defective fabric product. According to a technique disclosed in JP-A-60-231850 (Japanese Patent Application No. 231850/60) and JP-A-63-85142, an inspecting apparatus is mounted on a loom for performing a field inspection for a woven cloth. However, this inspection is also unsatisfactory for eliminating a defect which is due to an error or failure in the warp insertion between the dents of a reed, because the inspection is done on the finished fabric.
In the apparatus disclosed in JP-A-64-14347, swingable pieces are interposed, respectively, between adjacent dents of a reed at a top portion thereof. When neither error nor failure occurs in the insertion of a warp, the associated swingable piece is caused to move out of a light beam path of a light-transmission type photoelectric sensor by the warp moved to the uppermost position thereof at a rotational angle of the loom where the warps are moved topmost. However, if some warp is not present at the inter-dent gap at the topmost position because of the occurrence of a warp breakage or slack, the swingable piece is not moved upwardly and remains at a position where the light beam path is thereby intercepted. With such an arrangement, the presence or absence of the warp between the dents of the reed can be detected with certainty.
However, the function of the apparatus disclosed in JP-A-64-14347 is to detect breakage of the warp, wherein the detection of the presence or absence of the intersection between the swingable piece and the light beam path must necessarily be performed during operation of the loom. Consequently, detection of error or failure in the insertion of the warps through the reed is performed only after the loom is restarted, which in turn means that the loom is stopped when a warp insertion error or failure is detected and then restarted, which unavoidably results in that defect of more or less severity makes its appearance on the woven cloth.